I have sinus %26 allergy issues and I told my ENT about the Zyrtec D and that I was taking it and she agreed that it should work with my condition and so far it has performed well. Also, prior to purchasing the Zyrtec D for the first time I consulted with the Pharmacist at Sam's about which Zyrtec products and which was better with my symptoms/condition. Additionally, contrary to the instructions I only need to take one a day in late morning and I'm good all day and evening. The results are pleasing and just be prepared that it's not on the shelf you must get it from the pharmacy and show ID.